Re: [GIT PULL 1/2] asm-generic: rework PCI I/O space access

From: Arnd Bergmann
Date: Tue Aug 10 2021 - 07:34:12 EST

On Tue, Aug 10, 2021 at 11:19 AM John Garry <john.garry@xxxxxxxxxx> wrote:
> On 04/08/2021 09:52, Arnd Bergmann wrote:
> This seems a reasonable approach. Do you have a plan for this work? Or
> still waiting for the green light?

I'm rather busy with other work at the moment, so no particular plans
for any time soon.

> I have noticed the kernel test robot reporting the following to me,
> which seems to be the same issue which was addressed in this series
> originally:
> config: s390-randconfig-r032-20210802 (attached as .config)
> compiler: clang version 13.0.0 (
> 4f71f59bf3d9914188a11d0c41bedbb339d36ff5)
> ...
> All errors (new ones prefixed by >>):
> In file included from drivers/block/null_blk/main.c:12:
> In file included from drivers/block/null_blk/null_blk.h:8:
> In file included from include/linux/blkdev.h:25:
> In file included from include/linux/scatterlist.h:9:
> In file included from arch/s390/include/asm/io.h:75:
> include/asm-generic/io.h:464:31: warning: performing pointer
> arithmetic on a null pointer has undefined behavior
> [-Wnull-pointer-arithmetic]
> val = __raw_readb(PCI_IOBASE + addr);
> So I imagine lots of people are seeing these.

Right, this is the original problem that Niklas was trying to solve.

If Niklas has time to get this fixed, I can probably find a way to work
with him on finishing up my proposed patch with the changes you